Universal Electric Radiator Fan Thermostat Relay Wiring Kit 3/8" NPT Temperature Sensor Switch 185°F On 175°F Off 12V with 30A Breaker

Thermostatic Radiator Fan Relay Wiring Harness Kit for Universal 12V Applications (Classic V8 / Hot Rod)

What it Does: The Universal Electric Radiator Fan Thermostat Relay Wiring Kit automates single electric cooling fan operation based on coolant temperature to eliminate parasitic drag and prevent engine overheating.

The Stock Mechanical Fan Weakness

Factory belt-driven mechanical fans and failing clutch assemblies create continuous parasitic horsepower drag while failing to deliver adequate airflow at low RPM and prolonged idle. In traffic or staging lanes, low water pump speeds reduce airflow across the radiator core, triggering heat soak, coolant boiling, and vapor lock. Furthermore, retrofitting electric fans without a dedicated relay harness risks melting factory switches and undersized harness wiring under heavy inductive electrical loads.

The Engineering Solution

This heavy-duty circuit delivers dedicated, uninterrupted battery voltage directly to your cooling fan via a sealed 12V automotive relay triggered by a precision 3/8" NPT brass temperature switch. Calibrated to close the circuit at 185°F and open at 175°F, it maintains optimal engine operating temperatures without overloading the vehicle charging system. An inline 30A auto-reset circuit breaker safeguards the circuit from thermal overload and current spikes, while high-conductivity pre-wired leads eliminate voltage drop.

What's Included

• 1 pre-wired harness with heavy-duty 12V relay and relay socket
• 1 30A auto-reset circuit breaker
• 1 temperature sensor switch, 3/8" NPT thread (185°F on / 175°F off)
• 1 brass thread adapter bushing
• 2 nuts and 4 mounting screws
• 4 ring terminals, 2 butt connectors, and 1 female spade terminal

Technical Specifications

Compatibility

• Chevrolet Small-Block & Big-Block V8 (265, 283, 327, 350, 396, 427, 454, 502)
• Ford Small-Block, FE & 385-Series V8 (260, 289, 302, 351W, 351C, 351M, 390, 428, 429, 460)
• Chrysler / Mopar LA, B & RB V8 (273, 318, 340, 360, 383, 400, 426, 440)
• Custom hot rods, street rods, classic trucks, and custom 12V vehicle conversions

Frequently Asked Questions & Fitment Warnings

Does this fit my engine?

Yes, this kit is universally compatible with any 12V system featuring an intake manifold, cylinder head, or radiator port that accommodates a 3/8" NPT sensor or larger using the included adapter bushing.

Does this kit include an electric fan?

No, the electric cooling fan is not included; this kit provides the electrical harness, relay, breaker, and thermostatic sensor switch only.

The Muscle & Street Rod Standard

Engineered to handle thermal cycling and high inductive loads under continuous hood temperatures, this relay harness delivers rock-solid electrical isolation to preserve your charging system and protect your high-performance engine investment.